Note: Descriptions are shown in the official language in which they were submitted.
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Tilt Wing Aircraft
FIELD OF THE INVENTION
The invention relates to a tilt-wing aircraft and to a method for the
operation thereof.
BACKGROUND OF THE INVENTION
Tilt-wing aircraft have been known in principle for a long time. The article
by
William F. Chana and T. M. Sullivan: "The Tilt Wing Design for a Family of
High
Speed VSTOL Aircraft", presented at the American Helicopter Society, 49th
Annual
Forum, St. Louis, Missouri, 19-21 May 1993 provides a good overview.
SUMMARY OF THE INVENTION
The object of the invention is to provide an improved tilt-wing aircraft.
The object is achieved by the subject matter of the independent claims.
Configurations of the invention are set out in the subclaims.
One aspect of the invention relates to a tilt-wing aircraft with a tail drive
and control
unit which is configured to generate a forward thrust and to also generate an
upwardly or downwardly directed thrust component and/or a laterally directed
thrust
component during hover flight of the aircraft.
A tail drive unit of this type can provide a particular proportion or even
most of the
forward thrust of the aircraft during cruise flight. The result of this is
that noise
emissions generated, for example, by front propellers attached to the tilt
wing are
displaced from the aircraft cabin to the tail.
Furthermore, due to the forward thrust generated by the tail drive unit, the
propellers
of the aircraft attached to the tilt wing can be optimised in respect of hover
flight and
climb flight, whereas the tail drive unit is optimised in respect of cruise
flight.
According to a further aspect of the invention, the tail drive and control
unit
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comprises a tail propeller creating an air flow against an empennage of the
aircraft.
The empennage can be of a conventional configuration, with an elevator and a
rudder, or can be configured, for example, as a V empennage.
According to a further aspect of the invention, the tail drive and control
unit has a
sheathed tail propeller. In this case, it can be configured as a sheathed tail
propeller
which can be pivoted about the vertical axis and the transverse axis of the
aircraft to
provide the necessary thrust components.
The drive of the tilt-wing aircraft can be of a conventional configuration,
with
turbines and a gear unit.
According to a further aspect of the invention, the tilt-wing aircraft
according to the
invention comprises a hybrid drive which has for each propeller of the
aircraft a
respective electric motor driving the propeller, and which has at least one
energy
generating module which is provided with an internal combustion engine and a
generator to generate electrical energy.
Since each propeller is driven by an electric motor, it is unnecessary to
connect the
two propellers provided for hover flight and climb flight to a transmission
shaft, as is
required in the case of a tiltrotor aircraft, for example of the type Bell-
Boeing V22
Osprey, to counteract the failure of an engine. In the invention, each
electric motor is
preferably configured to be redundant.
The power required for the drive can be provided via a motor or turbine unit
which is
common to all propellers, and the power can then be distributed in an
optimised
manner onto the propellers by an electric coupling, according to the mission
task. To
achieve a redundancy of the hybrid drive, a further aspect of the invention
provides
at least one further energy generating module.
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The electric motors used in the invention are preferably configured as a low-
inertia
direct drive of a high power intensity, as described in DE 10 2007 013 732 Al,
i.e. as
electric machines with permanent excitation which are particularly suitable
for a
direct drive of the propellers due to a high specific torque and power
intensity and to
a low moment of inertia.
According to a further aspect of the invention, a storage unit for electrical
energy is
provided. This unit can be used to power the electric motors driving the
propellers, at
least temporarily, additionally or alternatively. This also increases the
redundancy.
According to a further aspect of the invention, the one energy generating
module and
the further energy generating module are configured to be the same or similar.
This
measure makes it possible to achieve a modular construction, comprising a
plurality
of energy generating modules which are each provided with an internal
combustion
engine and a generator.
However, according to a further aspect of the invention, the further energy
generating module can be configured as a fuel cell unit. This fuel cell unit
can
provide current for charging the storage unit for electrical energy, or can
provide
additional current for the operation of the electric motors.
According to a further aspect of the invention, the electrical energy
generated by the
at least one energy generating module is distributed onto the electric motors
driving
the propellers, subject to operating requirements. In this respect, for
example the
electric motor which drives the tail rotor is supplied with more electrical
energy
during cruise flight than it requires during hover flight or climb flight.
Therefore, according to a further aspect of the invention, during cruise
flight most of
the electrical energy is supplied to the electric motor which drives the tail
propeller.
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In an extreme case, the entire forward thrust could also be provided by the
tail
propeller, in which case the front propellers attached to the tilt wing can be
optimised
in respect of low resistance during normal operation or can even be stopped
aerodynamically.
BRIEF DESCRIPTION OF THE FIGURES
FIG. I is a perspective view of a tilt-wing passenger aircraft according to
the
invention;
FIG. 2 shows an unmanned tilt-wing aircraft according to the invention;
FIG. 3 shows an unmanned tilt-wing aircraft according to the invention, where
Fig.
3A is a side view of the aircraft in climb flight, Fig. 3B is a front view of
the aircraft
in hover flight, Fig. 3C is a plan view of the aircraft in climb flight and
Fig. 3D is a
corresponding perspective view, and Fig. 3E is a perspective view of the
aircraft in
cruise flight;
FIG. 4 shows an unmanned tilt-wing aircraft according to the invention in
cruise
flight, where Fig. 4A is a side view, Fig. 4B is a front view, Fig. 4C is a
plan view
and Fig. 4D is a perspective view;
FIG. 5 shows the flight control of a tilt-wing aircraft according to the
invention, Fig.
5A showing the pitch control, Fig. 5B showing the roll control and Fig. 5C
showing
the yaw control;
FIG. 6 (schematically) shows a hybrid drive for a tilt-wing aircraft according
to the
invention; and
FIG. 7 (schematically) shows a further hybrid drive for a tilt-wing aircraft
according
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to the invention.
DETAILED DESCRIPTION OF EMBODIMENTS
The illustrations in the figures are schematic and are not to scale.
Identical or corresponding reference numerals are used for identical or
similar
elements.
Fig. I shows a tilt-wing aircraft 10 according to the invention configured as
a
passenger aircraft. The aircraft comprises a fuselage 12, a tilt wing 14 to
which are
attached a front propeller 16 on the right-hand side and a front propeller 18
on the
left-hand side, and also comprises a tail propeller 20 which creates air flow
against
an empennage which comprises a horizontal tail plane 22 and a rudder unit 26.
Fig. 1
also schematically shows a nose wheel 26 and a left side wheel 28 of the
aircraft.
Fig. 2 shows an unmanned aircraft, a so-called UAV (unmanned aerial vehicle)
which is configured as a tilt-wing aircraft 32 according to the present
invention.
UAVs of this type are also known as drones. Here, unlike, model aircraft for
example, a UAV is understood as meaning an aircraft which has sufficient load
bearing capacity and adequate flight characteristics for information and
mission
assignments, for example for the transportation and cameras for information
purposes, or for the transportation of weapons for mission purposes. The drone
32
has a fuselage 34, a tilt wing 36 and a sheathed tail propeller 38 consisting
of the
actual tail propeller 40 and a sheath 42. Front propellers 44 and 46 are
attached to the
tilt wing 36.
Fig. I shows the tilt wing 14 of the aircraft 10 in a cruise position, while
Fig. 2 shows
the tilt wing 36 of the drone 32 in the position for climb flight. For hover
flight, the
tilt wing is pivoted to such an extent that the leading and trailing edges
thereof (in the
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cruise flight position) are approximately located on the vertical axis of the
aircraft.
Fig. 3 illustrates the different flight states of a drone 32 which comprises a
tilt wing
36 and a flap 48 which is closed in cruise flight but is open during hover
flight or
climb flight to allow the tilt wing 36 to tilt.
Fig. 3A is a side view of the drone 32 in climb flight; Fig. 3B is a front
view of the
drone 32 in hover flight; Fig. 3C is a plan view of the drone 32 in climb
flight; Fig.
3D is a perspective view of the drone 32 in climb flight (with open flap 48);
and Fig.
3E is a perspective view of the drone 32 in cruise flight (with closed flap
48).
Fig. 4 illustrates the different flight states of a drone 48 which comprises a
fuselage
54, a tilt wing 56 and a sheathed tail propeller 58. Fig. 4A is a side view of
the drone
48 in cruise flight; Fig 4B is a front view of the drone which has a front
propeller 60
and a front propeller 62 on the tilt wing 56; Fig. 4C is a plan view of this
drone; and
Fig. 4D is a perspective view of this drone in cruise flight.
Fig. 5 illustrates the flight control of a tilt-wing aircraft 72 according to
the
invention, said tilt-wing aircraft 72 comprising a fuselage 74, a tilt wing
76, a
sheathed tail propeller 78 and two front propellers 80, 82 on the tilt wing
76. As can
be seen from the front view of Fig. 5B, the tilt wing 76 is also provided with
a left-
hand aileron 84 and a right-hand aileron 86.
As shown in Fig. 5A, the pitch control of the tilt-wing aircraft 72 is
achieved by the
production of an upwardly directed thrust vector component S by the sheathed
tail
propeller 78.
As shown in Fig. 5B, the roll control of the tilt-wing aircraft 72 (about the
longitudinal axis of the aircraft) is achieved by the production of thrust
vectors
produced by the ailerons 84, 86 and/or by the production of a different thrust
due to
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the front propellers 80, 82, as shown by the thrust vectors or thrust vector
components Si (directed downwards) and S2 (directed upwards).
As shown in Fig. 5C, the yaw control of the tilt-wing aircraft 72 according to
the
invention is achieved by the provision of a laterally (sideways) directed
thrust vector
component S3 by the sheathed tail propeller 78.
Fig. 6 schematically shows a hybrid drive for a tilt-wing aircraft according
to the
invention. Via a shaft 94, an internal combustion engine 92 drives a generator
96
which sends electric current 98 via a line 98 to a central control unit 100.
The central
control unit 100 distributes the generated electrical energy as required or
depending
on the operating state via a first line 102 to an electric motor 104 which
drives a first
front propeller 106, and/or via a line 108 to a second electric motor 110
which drives
a second front propeller 112, and/or via a line 114 to a third electric motor
116 which
drives a tail propeller 118. Furthermore, the control unit 100 can supply
current to a
battery 120 via a line 122, but can also take current from said battery 120 to
support
the operation of at least one of the electric motors 104, 110, 116 (so-called
õboost").
Internal combustion engine 92 and generator 96 form an energy generating
module.
The internal combustion engine can be, for example a Wankel engine, a piston
engine or a turbine.
As electric engines, the electric motors 104, 110, 116 can be configured
considerably
smaller and lighter than mechanical turbo or motor drive units.
The electrical energy generated by the energy generating module 92, 96, being
optimised in respect of the respective operating state, is distributed onto
the electric
motors 104, 110, 116. The electric motors have the further advantage that
their speed
can be varied much faster than is the case for an internal combustion engine
as a
driving motor.
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A further advantage is seen in the fact that since electric motors are of a
considerably
smaller and lighter construction as electric engines, as described above,
tilting
mechanisms for the tilt wing as well as engines generating lift and forward
thrust can
be configured in a substantially simplified manner.
Fig. 7 shows an embodiment of the hybrid drive according to the invention in
which,
compared to Fig. 6, two additional energy generating modules 130, 134 and 138,
142
are provided, as well as corresponding lines 136, 144. As in Fig. 6, the first
energy
generating module comprises an internal combustion engine 92 which drives a
generator 96 via a shaft 94. The second energy generating module in Fig. 7
comprises an internal combustion engine 130 which drives a generator 134 via a
shaft 132. The third energy generating module in Fig. 7 has an internal
combustion
engine 138 which drives a generator 142 via a shaft 140.
Depending on operating requirements, the three energy generating modules 92,
96;
130, 134; 138, 142 can be in operation simultaneously, or it is also possible,
for
example, for one of these three energy generating modules to be disconnected
or to
be idling on standby.
Furthermore, for example, two of these energy generating modules can operate
with
full power to power the three electric motors 104, 110, 116 in each case
according to
the requirements existing there, divided up by the central control unit 146 in
Fig. 7.
Furthermore, for example in cruise flight, only the electric motor 116 for the
tail
propeller 118 can be operated with full power, whereas the electric motors
104, 110
for the front propellers 106, 112 are operated with reduced power so that
these
propellers do not provide any unnecessary resistance to the forward thrust.
To increase redundancy and reliability, but also to briefly increase the power
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(,,boost"), electrical energy can be used which, in the case of the hybrid
drive of Fig.
7, is supplied by the battery 120, or is supplied to the control unit 146 via
a line 148
from a fuel cell unit 150.
In addition, it is pointed out that the terms õcomprising" and õhaving" do not
exclude
any other elements or steps, and õa" does not exclude a plurality.
Furthermore,
features or steps which have been described with reference to one of the above
embodiments can also be used in combination with other features or steps of
other
embodiments described above. Reference numerals in the claims are not to be
considered as restrictive.
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LIST OF REFERENCE NUMERALS
passenger aircraft
12 fuselage
5 14 tilt wing
16 front propeller
18 front propeller
tail propeller
22 horizontal tail plane
10 24 rudder unit
26 nose wheel
28 side wheel
32 drone (UAV, Unmanned Aerial Vehicle)
15 34 fuselage
36 tilt wing
38 sheathed tail propeller
tail propeller
42 sheath
20 44 front propeller
46 front propeller
48 flap
52 drone
25 54 fuselage
56 tilt wing
58 sheathed tail propeller
front propeller
62 front propeller
30 64
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66
68
72 tilt-wing aircraft
5 74 fuselage
76 tilt wing
78 sheathed tail propeller
front propeller
82 front propeller
10 84 aileron
86 aileron
88
S, S 1, S2, S3 thrust vectors
15 92 internal combustion engine (VM; VM I)
94 shaft
96 generator (GEN; GEN 1)
98 line
100 control unit
20 102 line
104 electric motor 1
106 front propeller
108 line
110 electric motor 2
25 112 front propeller
114 line
116 electric motor 3
118 tail propeller
120 battery unit
30 122 line
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124
126
128
130 internal combustion engine 2
132 shaft
134 generator 2
136 line
138 internal combustion engine 3
140 shaft
142 generator 3
144 line
146 control unit
148 line
150 fuel cell unit
